Ozone is being given attention as a strong and clean oxidizing agent. In particular, the use of ozone for water treatment is increasing because the decomposition product thereof is oxygen and the residue thereof does not remain in the treated material, which is different form chlorine series oxidizing agents which have conventionally used and because the decomposition rate thereof is fast.
A discharging process and an electrolytic process have been mainly employed to generate ozone which is useful as an oxidizing agent as described above. For water treatment, etc., the practice is to contact the ozone-containing gas with the water being treated. In many cases, the general practice has to supply gaseous ozone to a mixing tank through, e.g., a filter to remove impurities with the filter and also to disperse the gaseous ozone in the water being treated. Many filters such as Rasching rings, etc., made from a corrosion resistant material have been used as conventional filters used for the above purpose. The ozone seems to be almost completely dissolved in the water to generate uniform ozone water which does not contain any gaseous ozone. However, since the solubility of ozone itself in water is low and ozone exists in the form of bubbles, ozone cannot be sufficiently dispersed in water by this method.
In the case of the electrolytic process, a special method that the water being treated is directly sent into the anode chamber of the electrolytic cell is proposed. However, an electrode material, etc., often contaminates the water. Moreover, another critical problem that the cell is damaged with impurities contained in the water occurs.
Production of ozone water having a higher concentration is preferred to utilize efficiently the ozone formed by an electrolysis or to discharge and treat water being treated in a short period of time. Thus, the development of a process and apparatus capable of easily producing ozone water having a high concentration has been desired.